scholarly journals Propagation Models for the Characterization of the Indoor UWB Channel

10.5772/20171 ◽  
2011 ◽  
Author(s):  
Francisco Saez de Adana
Keyword(s):  
Propagation Models ◽  
Uwb Channel

scholarly journals Experimental Characterization of Ultra-Wideband Channel Parameter Measurements in an Underground Mine

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
B. Nkakanou ◽  
G. Y. Delisle ◽  
N. Hakem
Keyword(s):  
Underground Mining ◽  
Path Loss ◽  
Measurement Procedure ◽  
Ultra Wideband ◽  
Small Scale ◽  
Scale Parameters ◽  
Channel Parameter ◽  
Channel Parameters ◽  
Uwb Channel

Experimental results for an ultra-wideband (UWB) channel parameters in an underground mining environment over a frequency range of 3 GHz to 10 GHz are reported. The measurements were taken both in LOS and NLOS cases in two different size mine galleries. In the NLOS case, results were acquired for different corridor obstruction angles. The results were obtained during an extensive measurement campaign in the UWB frequency, and the measurement procedure allows both the large- and small-scale parameters such as the path loss exponent, coherence bandwidth, and so forth, to be quantified. The capacity of the UWB channel as a function of the physical depth of the mine gallery has also been recorded for comparison purposes.

scholarly journals Research on Trust Propagation Models in Reputation Management Systems

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Zhiyuan Su ◽  
Mingchu Li ◽  
Xinxin Fan ◽  
Xing Jin ◽  
Zhen Wang
Keyword(s):  
Past History ◽  
Three Dimensions ◽  
Reputation Management ◽  
Reputation Systems ◽  
Propagation Models ◽  
Trust Propagation ◽  
Critical Measure ◽  
Media Systems ◽  
Remote Past

Feedback based reputation systems continue to gain popularity in eCommerce and social media systems today and reputation management in large social networks needs to manage cold start and sparseness in terms of feedback. Trust propagation has been widely recognized as an effective mechanism to handle these problems. In this paper we study the characterization of trust propagation models in the context of attack resilience. We characterize trust propagation models along three dimensions: (i) uniform propagation and conditional propagation, (ii) jump strategies for breaking unwanted cliques, and (iii) decay factors for differentiating recent trust history from remote past history. We formally and experimentally show that feedback similarity is a critical measure for countering colluding attacks in reputation systems. Without feedback similarity guided control, trust propagations are vulnerable to different types of colluding attacks.

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